Windows having sliding sash comprise a frame having a top, bottom and side members, two of which have parallel grooves therein in which the opposite side edges of the sash slide. In the case of vertically hung or slidable sash, the grooves are in the side members of the frame, which side members are called jambs. The frames are mounted in building openings which are bounded by rough structural members to which the frames are fastened. In the case of wood frame buildings, for example, the building openings are bounded by 2.times.4's, and the frames are fastened thereto by nailing the jambs to the 2.times.4's. Most building openings are inaccurately made and the sides thereof are not exactly parallel. In addition, the side members, particularly when 2.times.4's, may have a bow therein, so that the jambs of the frames nailed thereto are pulled out of parallel. When the sash receiving grooves are not parallel, the sash have sideplay when they are opened, with the result that they rattle when subjected to vibration. Vertically slidable sash are made to stay in any opened position in which they are placed, by structures called sash balances. Sash balances in some instances are merely a pair of weights, each of which are connected to the sash by a cord which extends from the weight over a pulley in the top of the jamb and then down to an anchor in the sash. In other instances, sash balances have comprised a spring inside a vertically extending housing that is fixed to the side of the jamb, and which has an extensible member that is fixed to the sash.
An object of the present invention is the provision of a new and improved vertically hung sash that is rattle free even when the jambs between which it is installed are considerably bowed or out of parallel.
Another object of the invention is the provision of a rattle free vertically hung sash of the above mentioned type in which the sash has sufficient clearance with respect to one of the jambs in which it is received so that it can be moved sideways a sufficient distance to bring the opposite edge of the sash out of its sash receiving groove to thereby permit the sash to be removed from the window frame, and in which the sash is normally and automatically held centered in a manner accommodating a large amount of nonparallelism of the jambs.
A further object of the invention is the provision of a new and improved structure of the above described type in which the centering, and the jamb clearance accomodating function is performed by structure that is part of the balance structure.
Further objects and advantages of the invention will become apparent to those skilled in the art to which the invention relates from the following description of several preferred embodiments that are described with reference to the accompanying drawings forming a part of the present disclosure.